First you have to define what a “good” AR-15 means to you. You can purchase AR-15s for thousands of dollars or you could build your own for hundred. It all depends on your level of comfort with building your own.
If you’re building your own AR, you can go straight from scratch, with an 80 lower, mill it yourself, put in the lower parts kit, complete the upper, barrel, etc. You can purchase 100% mil-spec parts all over the internet, including on our site! Of course, this takes time, effort, and precision. Simply finishing an 80% lower receiver can take hours. You can cut down on some costs by completing a lower, then purchasing a complete upper receiver assembly. With this, no paperwork is required. When it is all said and done, you could be looking at $500 – $900 dollars.
If money is no object, you can always purchase and AR-15 at your local gun shop. There are usually incredibly knowledgeable individuals who are happy to help you find the right AR for you.
If you have both time, and money, you can purchase parts for an AR-15 that could reach thousands of dollars. Just doing a simple internet search, you can find a stripped AR-15 lower that runs $200 or more. So really, whatever you dream up, you can piece together online. Any color, style, weight you can dream of, you can find. All you have to do is look.